Inheriting R6700 - New to Netgear - need some advice

I am a ASUS RT-86U Merlin user so I am new to Netgear equipment.
In the process of switching my parents off of Verizon cable TV & towards YouTube or Sling type streaming TV.
Was going to put them on an ASUS Blue Cave router for ease & range capability but my brother has an unused R6700 that he wants to give to them as a expense savings.

So my questions regarding the R6700:

1) still capable as a router for 1080p HD streaming TV (not 4k) ?
2) still capable to handle multiple streams - by AARP users ?
3) has good range to sustain higher end 2.4 Ghz speeds (4K sqft house with some WiFi IoT devices)?
4) what 3rd party firmware is available that is user friendly to administrate - nothing fancy but security is prioritize?
5) Is Netgear still supporting older router - again security is a priority?

1) still capable as a router for 1080p HD streaming TV (not 4k) ? Possible, depending upon kind of connection rate is acquired by TV.
2) still capable to handle multiple streams - by AARP users ?"The Netgear Nighthawk R6700 AC1750 Smart WiFi router boasts a 1GHz dual core processor, and provides up to 1750Mbps wireless thruput(450 Mbs N + 1300Mbs AC speeds).
It supports beamforming+ and external antennas for greater wireless network coverage. It supports prioritized bandwidth for lag-free gaming and prioritized bandwidth for streaming videos or music.
It is compatible with the "Netgear Genie" mobile App for iOS & Android, allowing for easy network setup, as well as streaming music or videos."
Should be good to go with streaming Netflix kind of videos.

3) has good range to sustain higher end 2.4 Ghz speeds (4K sqft house with some WiFi IoT devices)? Most single dual band routers can handle up to around 2000sq ft. Placement will be key and depending upon buildting materials, an extender maybe needed. Something like a EX7000.

4) what 3rd party firmware is available that is user friendly to administrate - nothing fancy but security is prioritize? Most 3rd party FWs are more advanced and not very end user friendly for the average home user. OpenWRT or DD-WRT. I would not recommend it unless you or someone can help configure it and help troubleshoot when needed.

1) still capable as a router for 1080p HD streaming TV (not 4k) ? Possible, depending upon kind of connection rate is acquired by TV.
2) still capable to handle multiple streams - by AARP users ?"The Netgear Nighthawk R6700 AC1750 Smart WiFi router boasts a 1GHz dual core processor, and provides up to 1750Mbps wireless thruput(450 Mbs N + 1300Mbs AC speeds).
It supports beamforming+ and external antennas for greater wireless network coverage. It supports prioritized bandwidth for lag-free gaming and prioritized bandwidth for streaming videos or music.
It is compatible with the "Netgear Genie" mobile App for iOS & Android, allowing for easy network setup, as well as streaming music or videos."
Should be good to go with streaming Netflix kind of videos.

3) has good range to sustain higher end 2.4 Ghz speeds (4K sqft house with some WiFi IoT devices)? Most single dual band routers can handle up to around 2000sq ft. Placement will be key and depending upon buildting materials, an extender maybe needed. Something like a EX7000.

4) what 3rd party firmware is available that is user friendly to administrate - nothing fancy but security is prioritize? Most 3rd party FWs are more advanced and not very end user friendly for the average home user. OpenWRT or DD-WRT. I would not recommend it unless you or someone can help configure it and help troubleshoot when needed.